J/ApJ/745/58 Light curves of the PMS eclipsing binary Par 1802 (Gomez+, 2012)
Luminosity discrepancy in the equal-mass, pre-main-sequence eclipsing binary
Par 1802: non-coevality or tidal heating?
Gomez Maqueo Chew Y., Stassun K.G., Prsa A., Stempels E., Hebb L.,
Barnes R., Heller R., Mathieu R.D.
<Astrophys. J., 745, 58 (2012)>
=2012ApJ...745...58G 2012ApJ...745...58G
ADC_Keywords: Binaries, eclipsing ; Photometry, VRI ; Photometry, infrared ;
Stars, double and multiple
Keywords: binaries: eclipsing - stars: fundamental parameters -
stars: individual (Parenago 1802) - stars: low-mass -
stars: pre-main sequence
Abstract:
Parenago 1802, a member of the ∼1 Myr Orion Nebula Cluster, is a
double-lined, detached eclipsing binary in a 4.674 day orbit, with
equal-mass components (M2/M1=0.985±0.029). Here we present
extensive VICJHKSlight curves (LCs) spanning ∼15 yr, as well as a
Keck/High Resolution Echelle Spectrometer (HIRES) optical spectrum.
The LCs evince a third light source that is variable with a period of
0.73 days, and is also manifested in the high-resolution spectrum,
strongly indicating the presence of a third star in the system,
probably a rapidly rotating Classical T Tauri star. We incorporate
this third light into our radial velocity and LC modeling of the
eclipsing pair, measuring accurate masses (M1=0.391±0.032 and
M2=0.385±0.032M☉), radii (R1=1.73±0.02 and
R2=1.62±0.02R☉), and temperature ratio
(Teff,1/Teff,2=1.0924±0.0017). Thus, the radii of the eclipsing
stars differ by 6.9%±0.8%, the temperatures differ by 9.2%±0.2%,
and consequently the luminosities differ by 62%±3%, despite having
masses equal to within 3%. This could be indicative of an age
difference of ∼3x105yr between the two eclipsing stars, perhaps a
vestige of the binary formation history. We find that the eclipsing
pair is in an orbit that has not yet fully circularized,
e=0.0166±0.003. In addition, we measure the rotation rate of the
eclipsing stars to be 4.629±0.006 days; they rotate slightly faster
than their 4.674 day orbit. The non-zero eccentricity and
super-synchronous rotation suggest that the eclipsing pair should be
tidally interacting, so we calculate the tidal history of the system
according to different tidal evolution theories. We find that tidal
heating effects can explain the observed luminosity difference of the
eclipsing pair, providing an alternative to the previously suggested
age difference.
Description:
We present the LCs of Par 1802 in V (with a total of 2286 data
points), IC (3488), J (564), H (176), and KS (365). The IC data
cover the largest time span, from 1994 December to 2009 January; it
includes the previously published LC (Paper II; 2008Natur.453.1079S 2008Natur.453.1079S)
and 1279 new data points obtained between 2007 March and 2009 January.
The V LC includes data obtained between 2001 January and 2009 January
with the 0.9m telescope at KPNO and with the SMARTS 0.9m, 1.0m, and
1.3m telescopes at CTIO. Using the ANDICAM instrument which allows for
simultaneous optical and near-infrared imaging, Par 1802 was observed
photometrically with the SMARTS 1.3m telescope at CTIO between 2005
February and 2008 February, constituting the entirety of the JHKS LCs.
Objects:
----------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
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05 35 11.14 -05 36 51.2 Par 1802 = V* V2212 Ori (P=4.67390)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 25 2286 Differential V-band Light Curve of Par 1802
table3.dat 25 3488 Differential Ic-band Light Curve of Par 1802
table4.dat 19 564 Differential J-band Light Curve of Par 1802
table5.dat 19 176 Differential H-band Light Curve of Par 1802
table6.dat 19 365 Differential Ks-band Light Curve of Par 1802
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See also:
II/171 : Parenago Catalog of Stars in Orion Nebula (Parenago 1954)
J/AZh/88/143 : Cat. of Stars in Orion Nebula - ORICAT (Vereshchagin+, 2011)
J/AJ/129/363 : Spectroscopy in Orion Nebula Cluster (Sicilia-Aguilar+, 2005)
J/AJ/121/3160 : JHK photometry near the Trapezium region (Carpenter+, 2001)
J/A+A/375/130 : New PMS spectroscopic binaries in Orion (Covino+ 2001)
J/AJ/117/2941 : Rotation periods of Orion PMS stars (Stassun+, 1999)
J/AJ/116/1816 : JHKLMNOPQ photometry in Orion cluster (Hillenbrand+, 1998)
J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d HJD Heliocentric Julian Date (HJD-2400000)
14- 19 F6.3 mag DVmag Differential V band magnitude
21- 25 F5.3 mag e_DVmag The 1σ error in DelVmag
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d HJD Heliocentric Julian Date (HJD-2400000)
14- 19 F6.3 mag DIcmag Differential Ic band magnitude
21- 25 F5.3 mag e_DIcmag The 1σ error in DelImag
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d HJD Heliocentric Julian Date (HJD-2400000)
14- 19 F6.3 mag DJmag Differential J band magnitude
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d HJD Heliocentric Julian Date (HJD-2400000)
14- 19 F6.3 mag DHmag Differential H band magnitude
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d HJD Heliocentric Julian Date (HJD-2400000)
14- 19 F6.3 mag DKsmag Differential Ks band magnitude
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History:
From electronic version of the journal
References:
Cargile et al. Paper I 2008ApJ...674..329C 2008ApJ...674..329C (Discovery of Par 1802 as a
low-mass, PMS eclipsing binary in the Orion star-forming region)
Stassun et al. Paper II 2008Natur.453.1079S 2008Natur.453.1079S (Surprising dissimilarities
in a newly formed pair of "identical twin" stars)
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jul-2013